The state Department of Energy and Environmental Protection is forecasting unhealthy air quality for “sensitive groups” from Wednesday through Saturday due to predicted elevated ground-level ozone pollution for southern Fairfield, southern New Haven, southern Middlesex and southern New London counties. These areas are expected to experience unhealthy air quality for “sensitive groups," DEEP said in a news release. 

“As Connecticut prepares for Memorial Day weekend and temperatures begin to warm up this week, we are expecting air quality that could impact our most susceptible residents, including children, the elderly and those with respiratory disease such as asthma,” Commissioner Rob Klee said. “If you do venture out to one of our beautiful state parks or forests this weekend. I hope everyone will do their part to help improve air quality by car-pooling and arriving early.” 

Multi-day air quality alerts have been rare in recent years, DEEP said. However, in October 2015 the U.S. Environmental Protection Agency lowered the national air quality standard for ground level ozone from 75 parts per billion to 70 parts per billion. As science evolves our understanding of ozone increases, which resulted in EPA setting a more protective ozone standard that may lead to an increase in the number of forecasted unhealthy air quality days in Connecticut this summer even though our air quality has steadily improved through the years, DEEP said. 

Ground level or "bad" ozone primarily occurs during warm summer days. Strong sunshine causes chemical reactions of air pollutants emitted from motor vehicles, power plants and industry and household activities, forming ozone. Warmer weather can bring high levels of ground level ozone and fine particulate matter. These two air pollutants pose serious health risks – especially to young children, the elderly, adults who are active outdoors, and people with respiratory disease. 

Unhealthy concentrations of ground level ozone can cause or make worse a variety of respiratory and other health problems including breathing difficulty, coughing, and throat irritation and worsen asthma episodes. Peak ozone levels are between noon and 8 p.m.